1. Field of the Invention
This present invention relates to watercraft control mechanism, and more particularly to watercraft control mechanism that provide enhanced, integrated steering, decelerating and trimming.
2. Description of Related Art
In recent years, the demands of racers and recreational users alike for greater performance and maneuverability have driven the designers of watercraft to reconsider the control mechanisms used for steering, decelerating and trimming. Various mechanisms are known for steering, decelerating and trimming watercraft and the mechanisms may used alone or in combination.
A watercraft may be steered by either turning the propulsion source, such as an outboard motor or a jet-propulsion nozzle, or by actuating control surfaces, such as a rudder or flaps or tabs, of the personal watercraft. The rudder generally defines a substantially vertical control surface and the flaps or tabs generally define either a horizontal or vertical control surface. U.S. Pat. Nos. 4,615,290 and 4,632,049 to Hall et al. and U.S. Pat. No. 4,352,666 to McGowan disclose steering mechanisms including vertical fins and rudders. U.S. Pat. No. 5,193,478 to Mardikian discloses steering mechanisms including horizontal tabs or flaps.
A watercraft may be decelerated by reversing thrust, redirecting thrust toward the bow of the watercraft, or by creating drag by introducing a control surface substantially perpendicular to the watercraft's direction of travel. Deceleration by reversing thrust is the most common technique, but the deceleration is slow due to the time lag required to stop and then reverse the propeller.
Decelerating by redirecting the thrust toward the bow is commonly done by placing a thrust-reversing bucket or reverse gate in the path of the water jet. U.S. Pat. Nos. 5,062,815, 5,474,007, 5,494,464, and 5,607,332 to Kobayashi et al. and U.S. Pat. No. 5,154,650 to Nakase disclose thrust-reversing buckets and reverse gates. Although these thrust-reversing buckets tend to direct the water jet forwards (toward the bow), they also direct the water jet downwards. The downwardly directed water jet lifts the stern of the watercraft and causes the bow to dive. The sudden diving of the bow makes the watercraft susceptible to flooding and instability and makes it difficult for the rider to remain comfortably seated and in control of the steering handle or wheel.
U.S. Pat. No. 5,092,260 to Mardikian discloses a watercraft control mechanism for a personal watercraft including a hinged, retractable flap mounted on each side of the hull and an actuator for angling the flaps into the water to slow the watercraft. The flaps pivot such that the trailing edge is lower than the leading edge, thereby creating an undesirable elevating force at the stern.
Trimming or stabilizing of watercraft is achieved by adjusting the angle of tabs mounted aft on the hull. Trim-tabs are used to alter the running attitude of the watercraft, to compensate for changes in weight distribution, and to provide the hull with a larger surface for planing. U.S. Pat. No. 4,854,259 to Cluett, U.S. Pat. No. 4,961,396 to Sasawaga, and U.S. Pat. No. 4,323,027 to Schermerhorn disclose trim-tab systems for watercraft. U.S. Pat. No. 4,749,926 to Ontolchik, U.S. Pat. No. 4,759,732 to Atsumi, U.S. Pat. No. 4,908,766 to Takeuchi, and U.S. Pat. No. 5,263,432 to Davis disclose trim-tab control systems that are actuated by electronic feedback control systems that sense the watercraft's pitch and roll, as well as wave condition, and make adjustments to the trim-tabs to stabilize the watercraft. The trim-tab control mechanisms deflect the water downward and thus elevate the stern. U.S. Pat. No. 4,967,682 to O'Donnell discloses a twin-trim-tab mechanism capable of deflecting the water under the hull either upwards or downwards to lower or elevate the stern, respectively. The twin-trim-tab mechanism is for stabilizing the watercraft and not for braking.
Steering, braking and trimming can be performed synergistically. U.S. Pat. No. 5,193,478 to Mardikian discloses an adjustable brake and control flaps for steering, braking and trimming a watercraft. The control flaps, located at the stern, in their fully declined position act as brakes for the watercraft. Differential declination of the control flaps results in trimming and steering of the watercraft. The control flaps provide steering, braking and trimming in a manner analogous to the flaps and ailerons of an aircraft. During braking, however, the downward sweep of the control flaps causes the stern of the watercraft to rise and the bow to dive, creating the potential for flooding and instability. Diving of the bow is uncomfortable for the rider and makes control of the watercraft during hard braking maneuvers more difficult.
U.S. Pat. No. 3,272,171 to Korcak discloses a control and steering device for a watercraft including a pair of vanes pivotally mounted to the hull that can be opened below the hull. The vanes are hinged at the ends closest to the stern and open toward the bow. As water is scooped by the opening vanes, the force of the water on the vanes forces the vanes to open even more. In order to prevent the vanes from being violently flung open against the underside of the watercraft, a ducting system in incorporated into the vanes to channel the scooped water through the rear of the vanes to cushion the hull from impact of the rear of the vanes. The scooping action of the vanes induces a great deal of turbulence on the underside of the watercraft, especially when braking at high speeds. The amount of water that is channeled through the ducting system is also minimal and thus braking might, in some conditions, be too harsh. The vanes and their associated attachment bases on the underside of the watercraft create drag at high speeds, even when fully retracted. The vanes are not integrated with the main steering mechanism, such as a rudder or a steerable nozzle, to provide better cornering. The vanes may also scoop up seaweed, flotsam or other objects floating in the water that may prevent the vanes from closing or clog the ducting system. Large gears must also be provided to retract and close the vanes when they are scooping water which adds weight to the rear of the watercraft and causes the rear of the watercraft to sag.
When the user stops applying the throttle, the motor speed (measured in revolutions per minute or RPMs) drops, slowing or stopping the flow of water through the nozzle of the jet propulsion unit at the rear of the watercraft and, therefore, reducing the water pressure in the nozzle. This is known as an “off-throttle” situation. Pump pressure will also be reduced if the user stops the engine by pulling the safety lanyard or pressing the engine kill switch. The same thing would occur in cases of engine failure (i.e., no fuel, ignition problems, etc.) and jet pump failure (i.e., rotor or intake jam, cavitation, etc.). These are known as “off-power” situations. For simplicity, throughout this application, the term “off-power” will also include “off-throttle” situations, since both situations have a similar effect on pump pressure.